US3715188A - Cholesterol assay and reagents therefor - Google Patents

Cholesterol assay and reagents therefor Download PDF

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Publication number
US3715188A
US3715188A US00139266A US3715188DA US3715188A US 3715188 A US3715188 A US 3715188A US 00139266 A US00139266 A US 00139266A US 3715188D A US3715188D A US 3715188DA US 3715188 A US3715188 A US 3715188A
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Prior art keywords
cholesterol
chromophore
sample
alcohol
formamide
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US00139266A
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J Denney
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INDIANA DEVELOPMENT FINANCE AUTHORITY
American Monitor Corp
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American Monitor Corp
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Assigned to MERCHANTS NATIONAL BANK & TRUST COMPANY OF INDIANAPOLIS, reassignment MERCHANTS NATIONAL BANK & TRUST COMPANY OF INDIANAPOLIS, SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). NOV. 3,1982 Assignors: AMERICAN MONITOR CORPORATION,
Assigned to SECURITY PACIFIC BUSINESS CREDIT INC. reassignment SECURITY PACIFIC BUSINESS CREDIT INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AMERICAN MONITOR CORPORATION AN IN CORP.
Assigned to MERCHANTS NATIONAL BANK & TRUST COMPANY reassignment MERCHANTS NATIONAL BANK & TRUST COMPANY RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: MERCHANTS NATIONAL BANK & TRUST COMPANY OF INDIANAPOLIS
Assigned to FOOTHILL CAPITAL CORPORATION, A CORP. OF CA reassignment FOOTHILL CAPITAL CORPORATION, A CORP. OF CA SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SECURITY PACIFIC BUSINESS CREDIT, INC.
Assigned to NEUBERGER AND BERMAN (LENDER), 522 FIFTH AVENUE, NEW YORK NEW YORK 10036 A NEW YORK LIMITED PARTNERSHIP reassignment NEUBERGER AND BERMAN (LENDER), 522 FIFTH AVENUE, NEW YORK NEW YORK 10036 A NEW YORK LIMITED PARTNERSHIP SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AMERICAN MONITOR CORPORATION
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Assigned to FOOTHILL CAPITAL CORPORATION, A CA. CORP. reassignment FOOTHILL CAPITAL CORPORATION, A CA. CORP. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AM DIAGNOSTICS, A CORP. OF IN
Assigned to AMERICAN MONITOR PARTNERS reassignment AMERICAN MONITOR PARTNERS SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: AM DIAGNOSTICS, A CORP. OF IN
Assigned to INDIANA DEVELOPMENT FINANCE AUTHORITY reassignment INDIANA DEVELOPMENT FINANCE AUTHORITY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AM DIAGNOSTICS, INC.
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/48Biological material, e.g. blood, urine; Haemocytometers
    • G01N33/50Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
    • G01N33/92Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving lipids, e.g. cholesterol, lipoproteins, or their receptors
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T436/00Chemistry: analytical and immunological testing
    • Y10T436/25Chemistry: analytical and immunological testing including sample preparation
    • Y10T436/25375Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.]
    • Y10T436/255Liberation or purification of sample or separation of material from a sample [e.g., filtering, centrifuging, etc.] including use of a solid sorbent, semipermeable membrane, or liquid extraction

Definitions

  • ABSTRACT A cholesterol assay, using formamide, which achieves the simplicity of a direct test of a specimen sample, yet which also achieves a comparable specificity and accuracy of cholesterol assays involving multiple-extraction steps.
  • the formamide destroys the cholesterol chromophore of a blank measurement, and this result may be compared with a companion cholesterol assay to eliminate the error caused by the chromophore of non-cholesterol chromogenic substances of the specimen; and the formamide also keeps the alcohol, which is used to prevent turbidity, from blocking the formation of the bilirubin portion of the noncholesterol chromogenic substances.
  • Cholesterol which is one of the fatty materials found in the blood serum, and which is formed primarily in the liver, is generally acknowledged to be very significant as a factor in various disease processes of the human body, including diseases of the heart, vascular system, etc.
  • the serum cholesterol level of an individual important but also it is important that the accuracy of the assay be close enough so as to reliably so detect any change which might occur from day to day, week to week, or month to month; since it is important to follow drug and diet therapy, and to detect cholesterol changes induced thereby, and/or changes of body response. If the test performed is not sufficiently reliable and specific, variation in some interfer ing substance might be falsely interpreted as a trend in cholesterol level, particularly since the interfering substances themselves change in concentration from time to time, and not at all always proportionately to any change of cholesterol.
  • Cholesterol reacts with strongly acid reagents to produce colored substances, chiefly cholestadiene sulfonic acids.
  • acetic acid and acetic anhydride are used as solvents and dehydrating reagents
  • sulfuric acid or sulfuric acid and ptoluenesulfonic acids are used as dehydrating and ox idizing reagents.
  • cholesterol is first attacked by strongly acid reagents, generalized as HX, where X" would be, for example, the sulfate ion or the acetyl radical.
  • HX strongly acid reagents
  • Such reagents first remove a molecule of water, then oxidize the intermediate to produce 3,5- cholestadiene (two double bonds).
  • the oxidizing agent is usually sulfuric acid, which is converted to sulfur dioxide.
  • the cholestadiene is attacked still further to form the dimer, bis-cholesta-3, S-diene, and is finally converted by the excess sulfuric acid, to a monoor disulfonic acid which is a highly colored molecule.
  • TWO-STEP PROCEDURES These methods introduce an extraction step, which extracts and partially isolates the cholesterol chromogen before chromophore or color development. For this reason, some of the interfering chromogens, especially protein, are removed, but the methods still are subject to error caused by non-specific chromogens, such as bilirubin which is extracted along with the cholesterol, and thus still provides a chromophore which is mistakenly measured as cholesterol chromophore.
  • Carr and Drekter that of Carr and Drekter"(7. Carr, 1.1., and Drekter, 1.1.: Clin Chem. 2:353, 1956.) is perhaps the best. Except for highly icteric samples (high bilirubin levels), it gives results that are in close correspondence to those obtained by more precise three-step methods; however, icteric samples are encountered with enough frequency as to create problems in routine analysis.
  • THREE-STEP PROCEDURES These involve an extraction of the cholesterol followed by a saponification of the esters before color development. Consequently, they do not suffer from serious error because of protein. Furthermore, the saponification step tends to destroy nonspecific chromogens such as bilirubin, resulting in significantly increased accuracy over two-step methods. This class of procedures is best exemplified by the method of Abell et al.;*- (8.
  • FOUR-STEP PROCEDURES These are the most complicated, but the most reliable procedures of the prior art, if their complexity does not introduce errors-which that very complexity makes possible.
  • the cholesterol is extracted, the esters are saponified, and the total cholesterol is then further purified by collection as the digitonide.
  • the digitonide is decomposed by saponification, which again frees the cholesterol, and the product of this step is subject to color development.
  • the present invention achieves a solution to goals which heretofore have appeared to be in effect contradictory to one another; that is, as now discussed, the present invention achieves substantially the simplicity of a direct test while nevertheless achieving specificity and accuracy comparable to those involving multipleextraction steps.
  • Formamide when present in a cholesterol reagent destroys the chromophore-forming reaction of the cholesterol chromogen at room temperature; however, the bilirubin chromogen does not completely form its chromophore as required for proper blank correction, at room temperature. It has been found that the formamide-cholesterol reagent must reach an elevated'temperature of about 80 C before sufficient chromophore formation from the bilirubin chromogen reaction will take place.
  • Formamide and a high molecular weight alcohol thus serve the desired function of preventing cholesterol chromophore development while allowing bilirubin chromophore development in a way in which turbidity is not observed; however, since the high molecular weight alcohols do not mix with the formamide, the formamide and alcohol must be added in two separate steps to the blank. This separateness of procedural steps is avoided in the present invention by the addition of the high molecular weight alcohol to the glacial acetic acid acetic acid sulfuric acid reagent.
  • the reagents are used in the following assay using a blank tube and a test tube:
  • the absorbence of the test so measured is proportional to the concentration of cholesterol in serum, for the interfering chromogens contribute equally to both test and blank; and since the blank is set at zero absorhence, the absorbence of the test is a measurement of the difference between (or in effect a subtraction of) blank from test.
  • 5TH EMBODIMENT Blank Reagent l Octyl, .nonyl, decyl, tridecyl, or hexadecyl alcohol.
  • Blank Reagent ll Formamide
  • Cholesterol Reagent As in lst Embodiment, except the alcohol is omitted.
  • the reagents are used in the following assay using a blank tube and a test tube;
  • An assay according to the novel concepts of the invention thus provides the multiple advantages of both simplicity corresponding to direct or one-step tests and accuracy of multiple-step or multiple-extraction tests, and also avoiding certain error-contributing aspects of the multiple-step processes.
  • the often-incompatible goals of both speed and accuracy are provided, along with relative ease and convenience of the test procedures, elimination of time and error of extraction steps while nevertheless attaining in effect the result of having fully performed such extractions to avoid a masking or other effect of the other chromophoreforming chromogens usually present in the sample or specimen being assayed.
  • the present invention provides a new and useful assay yielding quantitative determination of cholesterol in serum, plasma, or other biological material to be tested, and provides a method and reagents therefor, all having desired advantages and characteristics, and accomplishing the objects of the invention, including the objects and advantages hereinbefore pointed out and 'others which are inherent in the invention.
  • a process for the quantitative colorimetric or spectrophotometric determination of cholesterol in serum, plasma, or other biological material to be tested wherein the improvement comprises adding formamide to said material for preventing the formation of a chromophore from the cholesterol chromogen in the sample being assayed.
  • a process for the quantitative determination of cholesterol in serum, plasma, or other biological material to be tested wherein the improvement com- 0 prises adding formamide and a high molecular weight alcohol to said material for preventing the formation of chromophore from the cholesterol chromogen in the sample being assayed, while permitting the formation of the chromophore from the bilirubin chromogen.
  • a process for the quantitative determination of cholesterol in serum, plasma, or other biological material to be tested wherein the improvement comprises adding formamide to block the formation of the chromophore from the cholesterol chromogen in a first portion of the sample while causing the non-cholesterol chromogenic substances in the said first portion of the sample to produce their chromophores,
  • tridecl should read tridecyl This certificate supersedes Certificate of Correction d -October 23, 1973.

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  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Molecular Biology (AREA)
  • Engineering & Computer Science (AREA)
  • Urology & Nephrology (AREA)
  • Chemical & Material Sciences (AREA)
  • Biomedical Technology (AREA)
  • Immunology (AREA)
  • Hematology (AREA)
  • Medicinal Chemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Microbiology (AREA)
  • Biophysics (AREA)
  • Endocrinology (AREA)
  • Food Science & Technology (AREA)
  • Biotechnology (AREA)
  • Analytical Chemistry (AREA)
  • Cell Biology (AREA)
  • Biochemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Biological Materials (AREA)
  • Measuring Or Testing Involving Enzymes Or Micro-Organisms (AREA)
US00139266A 1971-04-30 1971-04-30 Cholesterol assay and reagents therefor Expired - Lifetime US3715188A (en)

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US13926671A 1971-04-30 1971-04-30

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US (1) US3715188A (https=)
CA (1) CA964174A (https=)
DE (1) DE2221158C3 (https=)
FR (1) FR2136763A5 (https=)
GB (1) GB1393724A (https=)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853473A (en) * 1972-08-30 1974-12-10 Medico Electronic Inc Reagent and method for urea determination
US3884638A (en) * 1973-08-01 1975-05-20 Damon Corp Method of determining cholesterol
US3894844A (en) * 1974-01-31 1975-07-15 American Cyanamid Co Simultaneous determination of triglycerides, cholesterol and phospholipids
US5380667A (en) * 1992-10-30 1995-01-10 The United States Of America As Represented By The Secretary Of The Air Force Serum bilirubin and liver function tests as risk predictors for coronary artery disease

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3558516A (en) * 1968-05-08 1971-01-26 Dow Chemical Co Cholesterol determination reagent of ferric perchlorate,sulfuric acid and ethyl acetate
US3615232A (en) * 1970-02-05 1971-10-26 Research Corp Method and reagent for determining total cholesterol in blood serum

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3558516A (en) * 1968-05-08 1971-01-26 Dow Chemical Co Cholesterol determination reagent of ferric perchlorate,sulfuric acid and ethyl acetate
US3615232A (en) * 1970-02-05 1971-10-26 Research Corp Method and reagent for determining total cholesterol in blood serum

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3853473A (en) * 1972-08-30 1974-12-10 Medico Electronic Inc Reagent and method for urea determination
US3884638A (en) * 1973-08-01 1975-05-20 Damon Corp Method of determining cholesterol
US3894844A (en) * 1974-01-31 1975-07-15 American Cyanamid Co Simultaneous determination of triglycerides, cholesterol and phospholipids
US5380667A (en) * 1992-10-30 1995-01-10 The United States Of America As Represented By The Secretary Of The Air Force Serum bilirubin and liver function tests as risk predictors for coronary artery disease

Also Published As

Publication number Publication date
DE2221158A1 (de) 1972-11-16
DE2221158C3 (de) 1981-11-12
DE2221158B2 (de) 1981-03-12
FR2136763A5 (https=) 1972-12-22
GB1393724A (en) 1975-05-14
CA964174A (en) 1975-03-11

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